Improved electrical characteristics of amorphous InGaZnO thin-film transistor with HfLaO gate dielectric by nitrogen incorporation

Abstract

A comparative study on the electrical characteristics of amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) with HfLaO and HfLaON gate dielectrics is conducted. With the appropriate incorporation of nitrogen into the HfLaO gate dielectric, the saturation mobility of the TFTs can reach 31.3 cm2 V−1 s−1, which is more than twice that of the control sample with the HfLaO gate dielectric, as a result of the passivation of traps at/near the dielectric/a-IGZO interface by the nitrogen incorporation. However, the electrical characteristics (such as saturation mobility, on-current, and on-current/off-current ratio) of the devices tend to deteriorate with excessive nitrogen incorporation owing to nitrogen-related defects generated in the dielectric.

Recent Developments of Flexible InGaZnO Thin‐Film Transistors

“…HfLaO is another potential candidate because not only does it possess a high dielectric constant, it also exhibits superior properties such as less Fermi-level pinning, large band offset to the conduction band, good thermal stability, and low trap density when compared to other binary oxides. [53,54]…”

Improved Performance of InGaZnO Thin-Film Transistor With Ti Incorporation Into La2O3 Gate Dielectric

“…With Ti incorporation, the electrical performance of sample B is superior to sample A, with µsat of 28.1 cm 2 V -1 s -1 , Ion of 515 µA , Ion/Ioff of 7.2×10 7 and SS of 0.17 V/dec. There are two factors that lead to these improvements.…”

“…6 in order to demonstrate the electrical reliability of all samples. For sample A with La2O3 gate dielectric, the electrical performance is relatively inferior with µsat of 22.2 cm 2 V -1 s -1 , on current (Ion) of 306 µA, on-off current ratio (Ion/Ioff) of 1.6×10 7 and SS of 0.23 V/dec. This is because the hygroscopicity and crystallization of La2O3 film result in high trap density (Nt = 3.5×10 12 cm -2 ), which had been proved by previous research (the same-way depositted La2O3 film exhibited polycrystalline structure with large surface roughness) [21] , and the trapped centers could induce Coulomb scattering on the charge carriers in the IGZO channel [22] .…”

“…Therefore, various high-k materials (e.g. HfO2, NbLaO, La2O3, HfLaO, and TaLaO [4][5][6][7][8] ) have been adopted as gate dielectric in IGZO TFT, aiming to lower its operating voltage and decrease the gate leakage current. Among them, La2O3 is of concern due to its high dielectric constant (~27) and large band gap (~6 eV), but La2O3 film is also hygroscopic and easy to crystallize, which induce more trap states at/near the dielectric/channel interface [6] .…”

Room-temperature-processed synaptic a-IGZO TFT with high-k HfLaO gate dielectric as neuromodulator

“…Consequently, synaptic thin-film transistors (TFTs) have been attracting attention because concurrent functions of neurotransmitters and neuromodulators can be easily implemented by their inherent three-terminal structures. In the past decade, amorphous indium-gallium-zinc oxide (a-IGZO)-based TFTs have been extensively developed due to the advantages of high carrier mobility, low manufacturing cost, flexibility, and large-area compatibility [9][10][11]. As the dominant contributor to the electrical conductance of a-IGZO, oxygen vacancies have been also reported as a key origin for memristive behaviors in oxide semiconductors, highlighting the potential of a-IGZO TFTs for synaptic devices.…”